Electric load changeover switch with movable contacts insertable in a rotary shaft, and arc discharge channels

ABSTRACT

An electric load switch, comprising a set of blocks each formed of an insulating material having fixed contacts located in them and a changeover shaft extending through these blocks with movable contacts mounted on it, wherein the switch is simple in design and comparatively small in size, reliable in operation, and easily assembled for a plurality of poles of an electric circuit due to the presence of unified or connectable elements.

United States Patent Nikolai Ivanovich Egorov ulitsa Lenina, 397/5, kv. 74;

Jury Grigorievich Kron, ulitsa Mira, 324A, kv. 4; Jury Ivanovich Moiseev, ulitsa Mira, 463, kv. 72; Jury Alexandrovich Putov, ulitsa Mira, 270, kv. 11, all of Stavropol,

Inventors U.S.S.R. Appl. No. 853,252 Filed Aug. 27, 1969 Patented Sept. 28, 1971 Priority Aug. 27, 1968 U.S.S.R. 1265425 ELECTRIC LOAD CHANGEOVER SWITCH WITH MOVABLE CONTACTS INSERTABLE IN A ROTARY SHAFI, AND ARC DISCHARGE CHANNELS 2 Claims, 10 Drawing Figs.

lU.S. Cl 200/155, ZOO/l0, 200/l 62 Int. Cl ..HOIh 19/40, I-l0lh 9/08 Field of Search. 200/ l 62,

166 E, 168 S, 171 A, II, 155, l4, l0

5 6] References Cited UNITED STATES PATENTS 2,440,578 4/1948 Dietrich 200 155 2,466,072 4 1949 Batcheller..... 200/155 2,3l8,488 5/1943 Hunteretal ZOO/l0 3,202,775 8 1965 Tillson 200/162 FOREIGN PATENTS 521,422 7 1953 Belgium 200 14 13,584 5 1911 France 200/155 485,208 10 1929 Germany 200/162 586,787 3/1947 GreatBritain. 2001155 433,559 10 1948 Italy ZOO/I62 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye AuomeyWaters, Roditi, Schwartz & Nissen ABSTRACT: An electric load switch, comprising a set of blocks each formed of an insulating material having fixed contacts located in them and a changeover shaft extending through these blocks with movable contacts mounted on it, wherein the switch is simple in design and comparatively small in size, reliable in operation, and easily assembled for a plurality of poles of an electric circuit due to the presence of unified or connectable elements.

PATENTEUsEPwsn 3,609.26?

SHEET 2 [1F 3 FIG. 5 FIE. 5

ELECTRIC LOAD CHANGEOVER SWITCH WITH MOVABLE CONTACTS INSERTABLE IN A ROTARY SHAFT, AND ARC DISCHARGE CHANNELS The present invention relates to commutation electric devices and, more particularly, to electric load changeover switches and is designated for connecting and disconnecting electric power circuits.

- Conventional electric load switches, for example knife switches, comprise a base plate made of an insulating material, assembled on which are fixed contact elements and a contact changeover rotor (shaft) installed on supports and provided along its axis with laterally extending profiles apertures in which movable contacts are secured by blade springs. In the above switches the moveable contacts are pressed in the closed position towards the springs by the fixed contacts, thus providing for the necessary contact pressure.

Such switches are rather bulky, have a large quantity of fastening elements (screws, nuts, washers), require for insulation base plates of different sizes, depending on the number of poles, and do not ensure the electrodynamic stability of the switch at short circuit currents, because the movable contacts touch the fixed ones with one side only. Also known are multipole electric changeover switches which are a set of blocks (packages) with fixed and movable contacts inside them which are switched by means of a common changeover shaft.

Such changeover switches are used for switching weak current circuits of secondary commutation and can not be used for switching off electric power loads.

Also known in the art is a movable contact consisting of at least two elongated contact elements spring pressed from opposite sides and bound with stop washers.

The above movable contacts are designed for high voltage disconnectors and can not be used in electric load switches without appropriate design changes in the device.

An object of the present invention resides in eliminating the aforesaid drawbacks.

A particular object of the present invention is to design an electric load switch simple in design and comparatively small in size, reliable in operation, easy to assemble, and consisting of standard elements, which will make it possible to easily assemble a switch for different number of poles of an electric circuit. These objects are achieved in the present electric load switch, comprising a set of blocks of an insulating material with fixed contacts and a changeover shaft disposed in said blocks, said shaft having along its axis a number of lateral apertures, each one of said apertures housing a movable contact made up of at least two elongated contact elements spring pressed from the the opposite sides and held together by means of locking devices, in which, in accordance with the present invention, the central parts of the blocks are made in the form of bushings through which the changeover shaft carrying the movable contacts is passed, and on the external sides of the bushings every block has, at least on one side, commutation channels for the outlet of the are when cutting out the electric load. In this case the butts of the bushings and the adjoining locking devices of the movable contacts have a shape which ensures that the bushing butts in the process of rotation of the shaft during the changeover of the switch are the guides for the locking device of the movable contacts and keep the latter in line with the fixed contacts.

It is expedient to make the butts of the bushings with shoul-. ders in the form of concentric grooves and the locking means (plates) of the movable contacts entering them with curvatures on the two opposite ends. The curvatures should correspond to the diameter of the concentric grooves.

The switch, made in compliance with the present invention, successfully solves the raised problems.

The switch of the present invention cuts down copper consumption, extends its service life as a result of a double break of each phase and deconcentration of friction surfaces. There is a visible phase break and, besides, a certain selection of the combination of fixed contacts and blocks makes it possible to use the switch as a two-way changeover switch.

The present invention will be better understood from the following detailed description of an embodiment thereof given by way of example with references to the appended drawings, in which:

FIG. 1 is a general view of a switch, according to the invention;

FIG. 2 is a cross section of FIG. I along lines lI-ll, the contacts being in the closed position;

FIG. 3 is the extreme block of the switch;

FIG. 4 is a cross section of FIG. 3 along line lV-IV;

FIG. 5 is an intermediate block of the switch;

FIG. 6 is a cross section of FIG. 5 along line Vl-VI;

FIG. 7 shows fixed and movable contacts of the switch in the closed position;

FIG. 8 is the changeover shaft of the switch;

FIG. 9 is a locking device of the movable contact;

FIG. 10 is a view of FIG. 8 along arrow A;

FIGS. 1 and 2 show that the present switch comprises blocks 1, 2, 3 and 4 connected with each other and insulating material, fixed contacts 5, clamped in the slots of the joining surfaces of these blocks, and a changeover shaft 6 made of an insulating material, with movable contacts 7 mounted on said shaft. The number of blocks is determined by the number of poles in the electric circuit. Described in the present embodiment is a three pole electric load switch in which blocks I and 4 are the extreme ones and blocks 2 and 3 are the intermediate ones.

The central parts of the extreme blocks 1 and 4 are made as bushings 8 (Figs. 3 and 4) whose butts on one side (on the side adjoining the movable contacts) carry shoulders in the fonn of concentric grooves 9 with arresters I0 to limit the travel of the movable contacts 7. The same side of the blocks I and 4 carry commutation channels 11 through which the electric arc, appearing during the changeover when the switch is energized, is thrown outside.

The intermediate blocks 2 and 3 are made similarly to the blocks 1 and 4, except that the butts of the bushings 8 are provided on both sides with concentric grooves 9 with arresters 10 (Figs. 5 and 6) and accordingly commutation channels I] are provided on both sides of the blocks 2 and 3.

The movable contact 7 of the switch consists of two parallel elongated contact elements 12 (FIG. 7), limit pins I3 carrying lugs 14 in their middle part, springs 15 and a locking device, for example plates 16. Each such movable contact 7 is mounted on the changeover shaft 6 in one of its apertures 17 (FIG. 8), provided along the axis of the shaft 6.

In the assembled position of the switch, the changeover shaft 6 carrying movable contacts 7 is passed through the bushings 8 of the blocks 1, 2, 3 and 4, and the plates 16 of the movable contacts 7 enter the adjoining concentric grooves 9 of the bushings 8. The plates 16 of the movable contacts 7 are made with curvatures 18 (FIG. 9) on the two sides of the contour in accordance with the diameter of the concentric grooves 9 and, as a result, in the process of rotation of the changeover shaft 6, when the switch is operated the bushings 8 are the guides for the plates 16. Thus, they ensure a centered fixation of the movable contacts and keep the latter in line with the fixed contacts. The plates 16 of the movable contacts 7 and the bushings 8 may have other configuration, for example, the butt of the bushing 8 may be made without a concentric groove and the plate 16 may be made as a bracket. In this case the bushing 8 will also be the guide for the adjoining bracket-shaped plate 16.

To set the changeover shaft 6 in the fixed position (ON, OFF one of its ends is supplied with recesses 19 (FIG. 10) which are entered during the rotation of the shaft by the appropriate locking arresters made in one of the extreme blocks 1 or 4 (not shown in the drawings). Installed on the butts of the extreme blocks 1 and 4 are mounting racks 20 (FIG. I), which are bound together with the blocks I, 2, 3 and 4 by pins 2I. The switch is set to the ON and OFF positions by a knob 22, which is connected with the changeover shaft 6. The switch may also be supplied with spark extinguishing chambers 23 which quench the electric arc thrown out from the commutation channels ll.

What is claimed is:

1. An electric load switch comprising: a set of adjacent blocks each made of an insulating material, the interior central portion of each block constituting a bushing, each said bushing having, on at least one exterior side of each of said blocks, commutation channels for the egress of electric arcs which are generated during the switching off of the electric load; fixed contacts located between each of said adjoining blocks; a rotatable changeover shaft formed of an insulating material axially extending through said bushings, said shaft including a plurality of lateral apertures along its axis; movable contacts located in each of said apertures of the changeover shaft, each of said movable contacts comprising at least two contact elements, spring means on opposite sides of said movable contacts, locking means connected to said spring means so as to have said spring means effect a compressive force on said contact elements, said locking means and the corresponding butts of said block bushings having complementary configurations so as to enable said bushing butts to form guide surface means for said locking means and to maintain said movable contacts in alignment with said fixed contacts.

2. An electric load switch as claimed in claim 1, wherein said bushing butts are each provided with axially extending shoulders, said shoulders forming concentric annular grooves, said locking means of the movable contacts comprising plates having curvatures on two opposite radial ends thereof, said curvatures corresponding to the radius of curvature of said concentric grooves and adapted to engage the surfaces of said grooves 

1. An electric load switch comprising: a set of adjacent blocks each made of an insulating material, the interior central portion of each block constituting a bushing, each said bushing having, on at least one exterior side of each of said blocks, commutation channels for the egress of electric arcs which are generated during the switching off of the electric load; fixed contacts located between each of said adjoining blocks; a rotatable changeover shaft formed of an insulating material axially extending through said bushings, said shaft including a plurality of lateral apertures along its axis; movable contacts located in each of said apertures of the changeover shaft, each of said movable contacts comprising at least two contact elements, spring means on opposite sides of said movable contacts, locking means connected to said spring means so as to have said spring means effect a compressive force on said contact elements, said locking means and the corresponding butts of said block bushings having complementary configurations so as to enable said bushing butts to form guide surface means for said locking means and to maintain said movable contacts in alignment with said fixed contacts.
 2. An electric load switch as claimed in claim 1, wherein said bushing butts are each provided with axially extending shoulders, said shoulders forming concentric annular grooves, said locking means of the movable contacts comprising plates having curvatures on two opposite radial ends thereof, said curvatures corresponding to the radius of curvature of said concentric grooves and adapted to engage the surfaces of said grooves. 